 /*******************************************************************************
  * Copyright (c) 2000, 2006 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.ui.externaltools.internal.variables;

 import org.eclipse.core.resources.IProject;
 import org.eclipse.core.resources.IResource;
 import org.eclipse.core.runtime.CoreException;
 import org.eclipse.core.runtime.IStatus;
 import org.eclipse.core.runtime.Path;
 import org.eclipse.core.runtime.Status;
 import org.eclipse.core.variables.IDynamicVariable;
 import org.eclipse.core.variables.IDynamicVariableResolver;
 import org.eclipse.osgi.util.NLS;
 import org.eclipse.ui.externaltools.internal.model.ExternalToolBuilder;
 import org.eclipse.ui.externaltools.internal.model.IExternalToolConstants;


 public class BuildProjectResolver implements IDynamicVariableResolver {

     /* (non-Javadoc)
      * @see org.eclipse.core.variables.IDynamicVariableResolver#resolveValue(org.eclipse.core.variables.IDynamicVariable, java.lang.String)
      */
     public String resolveValue(IDynamicVariable variable, String argument) throws CoreException {
         IResource resource= ExternalToolBuilder.getBuildProject();
         if (argument != null && resource != null) {
             resource = ((IProject)resource).findMember(new Path(argument));
         }
         if (resource != null && resource.exists()) {
             return resource.getLocation().toOSString();
         }
         abort(NLS.bind(VariableMessages.BuildProjectResolver_3, new String []{getReferenceExpression(variable, argument)}), null);
         return null;
     }
     
     /**
      * Throws an exception with the given message and underlying exception.
      *
      * @param message exception message
      * @param exception underlying exception or <code>null</code>
      * @throws CoreException
      */
     protected void abort(String message, Throwable exception) throws CoreException {
         throw new CoreException(new Status(IStatus.ERROR, IExternalToolConstants.PLUGIN_ID, IExternalToolConstants.ERR_INTERNAL_ERROR, message, exception));
     }
     
     /**
      * Returns an expression used to reference the given variable and optional argument.
      * For example, <code>${var_name:arg}</code>.
      *
      * @param variable referenced variable
      * @param argument referenced argument or <code>null</code>
      * @return vraiable reference expression
      */
     protected String getReferenceExpression(IDynamicVariable variable, String argument) {
         StringBuffer reference = new StringBuffer ();
         reference.append("${"); //$NON-NLS-1$
 reference.append(variable.getName());
         if (argument != null) {
             reference.append(":"); //$NON-NLS-1$
 reference.append(argument);
         }
         reference.append("}"); //$NON-NLS-1$
 return reference.toString();
     }
 }

